Conduit bending machine

ABSTRACT

A machine for forming integral bends in conduit is provided with a circular die-block carrying a circumferential groove on its outside diameter. The conduit to be formed is slipped over the die-block and four blades converging toward the center of the conduit form a circumferential indentation in the conduit in the plane of the circumferential groove of the die-block. The dieblock is then caused to move relative to an external die member, entraining the indentation in the conduit and crimping the entrapped material against the undeformed surface of the conduit. The center of the circumferential indentation is offset from the center of the conduit and therefore the sections of the conduit on either side of the completed crimp have an angular offset relative to one another.

United States Patent 1191 Koger, Jr. et al.

[111 3,831,421 [45] Aug. 27, 1974 CONDUIT BENDING MACHINE Inventors: Joseph A. Koger, Jr.; James L.

Wade, both of Martinsville, Va.

Assignee: Koger & Wade Manufacturing Corporation, Martinsville, Va.

Filed: June 26, 1972 Appl. No.: 266,460

US. Cl. 72/307, 72/369 Int. Cl B21d 9/14 Field of Search 72/307, 369

References Cited UNITED STATES PATENTS Primary Examiner-Lowell A. Larson Attorney, Agent, or Firm Lilling & Siege] ABSTRACT A machine for forming integral bends in conduit is provided with a circular die-block carrying a circumferential groove on its outside diameter. The conduit to be formed is slipped over the die-block and four blades converging toward the center of the conduit form a circumferential indentation in the conduit in the plane of the circumferential groove of the dieblock. The die-block is then caused to move relative to an external die member, entraining the indentation in the conduit and crimping the entrapped material against the undeformed surface of the conduit. The center of the circumferential indentation is offset from the center of the conduit and therefore the sections of the conduit on either side of the completed crimp have an angular offset relative to one another.

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PATENTEDAUBZ'IIHH SIIHSNE connurr BENDING MACHINE BACKGROUND OF THE INVENTION The invention relates to machines for the forming of integral bends in circular conduit whose diameter is relatively large compared to the wall thickness.

More particularly, the invention relates to such machines in which the desired bend is formed by creasing the conduit circumferentially and crimping the crease flat against an undeformed section of the conduit wall.

The teachings of the invention are particularly applicable to conduit of substantial diameter, for example, such as used for the pneumatic conveyance of particulate matter and obnoxious gases and vapors in exhaust systems.

It has been known in the prior to form bends in conduit of this type of forming a partial circumferential crease and crimping it, a machine for performing such operations being described in US. Pat. No. 1,032,152 of July 9, 1912. Such machines of the prior art, however, suffered from a number of shortcomings in the manner of forming the crimp and the manner of operating the machine, resulting in a large percentage of failure to achieve a sound bend, or to maintain the prescribed dimensions of the bend.

It is therefore a primary objective of the invention to describe a method of forming a crimped bend in a conduit in which the crimp runs around the full circumference of the conduit.

It is another objective of the invention to describe a machine, and controls for same, to carry out the method accurately and reliably.

It is a further objective of the invention to teach such structures and constructional elements as will result in a machine economical in cost and operable by unskilled personnel.

SUMMARY According to the instant invention a machine for the bending of conduit is provided with a die in the form of a cylindrical plunger, into whose external diameter a circumferential groove is machined. The conduit is I slipped over the plunger and a number of blades advance against the outside of the conduit and bulge it inwardly in the plane of the circumferential groove. The indentation thus formed is substantially circular with its center offset relative to the center of the undeformed portions of the conduit.

An external die is also provided, and carries an annular shoulder on its inner, circular, surface; the annulus opening in the direction of the of the indentation described above. By moving the plunger axially into the the opening of the external die, the entrapped material indented into the circumferential groove of the plunger is bent into the annular shoulder of the external die member and is creased to form a crimped seam. Since the indentation is offset relative to the axis of the conduit more material is trapped in the crimp on one side of the conduit than on the side diamterically opposed, thereby inducing an angular displacement of one end of the conduit relative to the other.

By varying the relative offset and depth of the indentation and hence the dimensions of the resulting crimp the angular relationship of the two segments of the conduit on either side of the crimp may be varied; by varying the number of crimps and their relative spacing a bend of arbitrary radius and total included angle may be produced.

The use of a fully circumferential crimp and the other advantages and improvements encompassed by the invention and described with reference to the accompanying drawing pennit much greater uniformity and control in the production of bends, elbows and offsets in conduit.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING The several features and advantages of the invention are illustrated in the accompanying drawing, in which:

FIG. 1 is a section of the preferred embodiment of the conduit bending machine;

FIGS. 2a and 2b are partial, sectioned views of the cooperating dies and blades of the preferred embodiment;

FIG. 3 is a top view of the embodiment of FIG. 1;

FIG. 4a is frontal, partially sectioned, view of the embodiment of FIG. 1;

FIG. 4b is a rear view of the preferred embodiment;

FIG. 5 is a schematic of the control circuits of the preferred embodiment; and

FIG. 6 is a schematic, partial section of the control board of the circuit of FIG. 5, taken along section-line 6-6.

DESCRIPTION OF THE PREFERRED EMBODIMENT A frame composed of four parallel beams is capped by endplate 101 at the forward end of the machine and plate 102 at the rearward end of the machine, and is supported on legs 110. A shaft 11 is reciprocably supported in journals 104 affixed to mounts 103 which, in turn are rigidly joined to lower beams 100. Motion of the shaft 11 is governed by hydraulic cylinder 30, connected to the shaft by yoke 50. The cylinder 30 is mounted on the plate 102 pierced with suitable openings for the passage of the yoke 50.

A die 10, in the form of a cylindrical plunger, is fixed to the end of the shaft 11 farthest from the yoke 50; a workpiece, in the form of a cylindrical section of conduit, l is slipped over the plunger 10 and received in one of the concentric recesses provided in the face of carrier 60, slideably journaled on the shaft 11 intermediate between the the end-plates 102 and 101.

The shaft 11, with the plunger 10 and the workpiece l, protrudes through a circular opening centered in the face of endplate 101, this opening being partly covered by a flange in which a tubular die 12 is mounted. The inner diameter of the die 12 is a snug fit over the outside diameter of the workpiece 1, with an annular canted relief of larger diameter machined into its forward edge.

The endplate 101 serves as a mounting for hydraulic cylinders 33, 34, and 35 which, in turn, impart reciprocating motion to blades l3, 14, 15 and 16.

The plunger 10 carries a circumferential groove on its external diameter; FIGS. 2a and 2b illustrate the manner in which the blades l3, l4, l5 and 16 cooperate with the aforementioned groove to indent the surface of the workpiece 1. In FIG. 2a blades 13 and 14 the others being omitted for the sake of clarity are shown in their advanced position protruding into the circumferential groove of the plunger and entraining a portion of the conduit 1 into the groove.

The internal edges of the blades are so shaped that at their greatest advance the aforementioned edges form a circular outline whose diameter is smaller than that of the unworked conduit, or workpiece, 1 and whose center is offset relative to that of the workpiece 1, in the direction of the blade 14. In this manner the indentation in the surface of the workpiece is deepest under the blade 13, least under the blade 14, and intermediate between these extremes, and equal, under the blades and 16.

Upon the completion of the circumferential indentation the several blades are withdrawn from the immediate vicinity of the conduit 1, into positions shown in FIG. 2b, and the hydraulic cylinder activated to move the shaft 11, along with plunger 10, in the direction of endplate 102. At the same time a brake mechanism, to be further described below with reference to FIG. 3, is activated to prevent the rearward motion of the carrier 60, thereby also preventing the workpiece 1 from moving.

As the plunger 10 moves towards the stationary annular die 12, with the segment 11) of the workpiece between the plunger and the carrier 60 stationary, the material indented into the groove of the plunger 10 is entrained in the groove and forced backward into contact with the unindented portion of the workpiece 1. The process is completed as the plunger 10 passes through the die 12, with the crimp in the wall of the conduit forced into the annular recess 112 in the leading edge of the die, thereby ensuring that the internal diameter of the conduit is maintained constant throughout the crimped area. Because the indentation in the conduit was deeper under the blade 13, more material is entrained in the crimp at that point than anywhere else around the circumference of the workpiece, and, correspondingly less at a point diametrically opposite, corresponding to the midpoint of the blade 14. Because of this excess material enfolded, the free end of the conduit 1 is canted relative to the original centerline towards the position of the blade 13; typically this angular rotation being of the order of l 1 AP.

Multiple repetition of the above process produces bends of considerable turning angle for example, eight crimps of ll% each result in a right-angled elbow. It being understood that the workpiece 1 is advanced out of the machine between each of the repeated crimps, the distance between successive bends determining the radius of curvature of the finished piece.

The mechanism used to accomplish the advance of the workpiece out of the die 12 is also shown in FIG. 1. The brake mechanism locking the carrier 60 to the frame of the machine is released and the carrier locked to the shaft 11 by means of ratchet plates 61 engaging ratchet teeth 111 machined in the surface of the shaft 11. The ratchet plates 61 are suspended from a hydraulic cylinder 37 by the yoke 62; the cylinder 37 being mounted on a frame 63 attached to rail 64. The rail 64 is affixed to the back face of the carrier 60 and forms a pocket for the guidance of the ratchet plates 61. The latter are of differing thicknesses and provided with a certain degree of freedom of relative movement, thereby ensuring that upon the actuation of the cylinder 37 in the downward direction at least one of them will be lined up with, and engaged by, the rack formed by teeth 111.

With the ratchet 61/1 1 l engaged, movement of the shaft 11 may be induced by suitably valving fluid under pressure into the appropriate chamber of the hydraulic cylinder 30 and the carrier 60 will entrain the workpiece 1 out of the die 12 and present a new segment of the conduit to be indented and crimped.

FlG. 3 is a plan view of the machine, the components of the ratchet mechanism described above being omitted for clarity of illustration, along with the workpiece 1.

The brake mechanism which is used to hold the workpiece 1 stationary during the crimping stroke includes cylindrical rails 112 and brake-arms 65, rotatably anchored to the backward face of carrier 60 at pivots 69. The rails 112 are parallel to the shaft 11 and are rigidly fixed in endplates 101 and 102; the outboard ends of the brake-arms 65 are provided with journals freely sliding on the rails 112 when the brake-arms are parallel to the back face of the carrier. The relative position of the brake-arms 65 and of the carrier 60 is regulated by a pair of hydraulic cylinders 38, whose piston rods are pivotally attached to the carrier and whose cylinders are rigidly affixed to the inboard ends of the brake-arms. Adjusting screws 66 are also provided to ensure that, upon the activation of the hydraulic cylinders 38 in one direction, the brake-arms 65 are rigidly held in a parallel relationship to the carrier 60. Upon the reversal of the direction of motion of the cylinders, or actuators, 38 the brake-arms 65 attempt to pivot at point 69 and force the journals on their outboard ends out of proper alignment with the rails 112, thereby locking the carrier against the stationary rails which form part of the frame of the machine.

Hence, by alternately energizing the cylinders 38 and the actuator 37, the carrier can be made fast to either the frame of the machine or to the shaft 11, or, by simultaneously disengaging both the brake and ratchet devices, be made freely slideable along the shaft 11. The latter condition is used to initially load the machine with the requisite length of conduit to form workpiece I.

FlG. 4a shows a frontal view of the machine; clearly indicating cylinders 33, 35 and 36 which provide for the reciprocal motion of the blades 13, 15 and 16. The mechanism for powering blade 14 is also shown, including ramped cams 34 mounted on the piston-rods of actuators 35 and 36. The cams 34 drive trains 134 made up of roller bearings inserted into races milled into a plate 144 which is affixed to the lower skirt of the endplate 101. Guides for the blade-mount are also milled into the plate 144 and the latter is impelled upward, carrying the blade 14 when the actuators 35 and 36 move inwardly and cause the cams 34 to ride over the ends of the roller-trains 134. Plungers at either of the trains 134 transmit the motion to the rollers and hence to the blade-mount 140; the blade 14 is disengaged from the workpiece 1 by gravity, once the restraint imposed on the outer ends of the trains 134 is removed by the withdrawal of the earns 34.

Several components of the hydraulic system which is used to actuate the cylinders 30, 33, 35, 36, 37 and 38 are also shown in the illustrations, including reservoir 74, pump 75, drive-motor 76 and valves 71, 72 and 73.

The control valves 71, 72 and 73 are governed in their function by electrical signals acting on electromagnets; these signals being derived from a control circuit shown in H6. 5. A switch 80 is used to control the supply of electrical power to the machine, including a motor 81 to whose shaft a number of rotary switches, forming the timing mechanism 82, are ganged. The shaft of motor 80 is also connected to a second bank of rotary switches, forming a timing mechanism 84, through a gear-train 83; these timing mechanisms 82 and 84 being so interconnected with each other and with the valves 71, 72, 73 and 74 that all possible cycles of the machine may be derived by their use.

The specific series of operations actually performed by the machine upon the insertion of a blank piece of conduit and the closure of the switch 80 is governed by control board 85. The control board 85 provides a large number of uniformly spaced electrical contacts, each of which is a spring-loaded switch-pin 87 mounted in a hinged cover. To set into motion the machine a rectangular piece of cardboard 86 is prepunched in a pattern corresponding to the connections it is desired to be made and interleaved between the board 85 and hinged cover 88. The pins 87 can only complete electrical contacts at places where the board 86 has been punched away to permit their passage to the contact elements in board 85.

As a guide to the operator, and to prevent errors, the logic of the timing mechanisms 82 and 84 is also wired into a display panel 89 on which a series of numbers correspodning to the conduit diameter, the bend magnitude in degrees, and the length of stock necessary for the product are displayed. The operator can tell at a glance whether the dies mounted in the machine, the stock available and the shop order calling for a specified product correspond to the numbers indicated on display panel 89 and can start the machine by depressing switch 80; the remainder of the manufacturing process is automatic.

As will be appreciated by those skilled in the art, elimination of twist definitely improves the quality of the product; and in a test run with our conduit bending machine of about 2,000 elbows, twist did not occur, and this is attributed to the device 144.

The invention disclosed above is not limited to the specific details described, some of which may be. altered within' the teaching of the disclosure by one skilled in the art.

What is claimed is:

l. A machine for forming integral bends in a cylindrical conduit, comprising: a frame and a cylindrical shaft reciprocably journaled in said frame; first hydraulic drive means, for reciprocating said cylindrical shaft; first die means including a cylindrical portion and an annular circumferential groove, rigidly affixed at one end of said cylindrical shaft; opposing pairs of blade means including a plurality of planar die elements reciprocably mounted in said frame about said first die means; second drive means, including a plurality of of hydraulic cylinders, two of which comprise an opposing pair, adapted to position said blade means so as to cooperatively form a planar circular opening in a plane orthogonal to said cylindrical shaft; second die means including a stepped circular annulus spaced from and surrounding said cylindrical shaft; and control means whereby said first hydraulic drive means positioning said cylindrical shaft carrying said first die means inside said conduit on one side of said second die means; one of said second drive means, driven by said opposing pair of hydraulic cylinders, transmits motion generated from said opposing pair of hydraulic cylinders to one of said planar die elements of said blade means by cam means and train means having a plurality of rolling elements; said second drive means positioning said blade means to form said planar circular opening in the plane of said annular circumferential groove, with the center of said circular opening offset from the center of the cylindrical portion of said first die means and the diameter of said circular opening being smaller than the diameter of said cylindrical portion; said die elements of said blade means each impressing a portion of the surface of said conduit into said annular circumferential groove completely around said conduit; said second drive means reciprocably positioning said blade means out of contact with said impressed portion of said conduit, and said first hydraulic drive means positioning said first die means on the other side of said second die means, and impelling said impressed portion of said conduit against said stepped circular annulus of said second die means, thereby forming an unsymmetrical crimp in the surface of said conduit as the free end of said conduit is canted relative to its original center line, whereby multiple operations or crimps produce a desired bend substantially without twist in said conduit.

2. The machine described in claim 1, further comprising a carrier, slideably journaled onsaid cylindrical shaft, for supporting one end of said conduit, and brake means for arresting motion of said carrier relative to said frame.

3. The machine described in claim 2, further comprising ratchet means, whereby said carrier may be locked against said cylindrical shaft.

4. The machine described in claim 1, in which said blade means comprise four reciprocating planar die elements, whose axes of reciprocating motion are mutually orthogonal.

5. The machine described in claim 3, in which said brake means and said ratchet means are governed by said control means.

6. The machine described in claim 1, wherein said train means comprises a plurality of cylindrical rollers disposed in a pair of tracks.

7. The machine described in claim 6, wherein said cam means include a pair of cams, each of which communicates indirectly with one of said pair of tracks for transmitting motion to said one of said planar die elements of said blade means. 

1. A machine for forming integral bends in a cylindrical conduit, comprising: a frame and a cylindrical shaft reciprocably journaled in said frame; first hydraulic drive means, for reciprocating said cylindrical shaft; first die means including a cylindrical portion and an annular circumferential groove, rigidly affixed at one end of said cylindrical shaft; opposing pairs of blade means including a plurality of planar die elements reciprocably mounted in said frame about said first die means; second drive means, including a plurality of of hydraulic cylinders, two of which comprise an opposing pair, adapted to position said blade means so as to cooperatively form a planar circular opening in a plane orthogonal to said cylindrical shaft; second die means including a stepped circular annulus spaced from and surrounding said cylindrical shaft; and control means whereby said first hydraulic drive means positioning said cylindrical shaft carrying said first die means inside said conduit on one side of said second die means; one of said second drive means, driven by said opposing pair of hydraulic cylinders, transmits motion generated from said opposing pair of hydraulic cylinders to one of said planar die elements of said blade means by cam means and train means having a plurality of rolling elements; said second drive means positioning said blade means to form said planar circular opening in the plane of said annular circumferential groove, with the center of said circular opening offset from the center of the cylindrical portion of said first die means and the diameter of said circular opening being smaller than the diameter of said cylindrical portion; said die elements of said blade means each impressing a portion of the surface of said conduit into said annular circumferential groove completely around said conduit; said second drive means reciprocably positioning said blade means out of contact with said impressed portion of said conduit, and said first hydraulic drive means positioning said first die means on the other side of said second die means, and impelling said impressed portion of said conduit against said stepped circular annulus of said second die means, thereby forming an unsymmetrical crimp in the surface of said conduit as the free end of said conduit is canted relative to its original center line, whereby multiple operations or crimps produce a desired bend substantially without twist in said conduit.
 2. The machine described in claim 1, further comprising a carrier, slideably journaled on said cylindrical shaft, for supporting one end of said conduit, and brake means for arresting motion of said carrier relative to said frame.
 3. The machine described in claim 2, further comprising ratchet means, whereby said carrier may be locked against said cylindrical shaft.
 4. The machine described in claim 1, in which said blade means comprise four reciprocating planar die elements, whose axes of reciprocating motion are mutually orthogonal.
 5. The machine described in claim 3, in which said brake means and said ratchet means are governed by said control means.
 6. The machine described in claim 1, wherein said train means comprises a plurality of cylindrical rollers disposed in a pair of tracks.
 7. The Machine described in claim 6, wherein said cam means include a pair of cams, each of which communicates indirectly with one of said pair of tracks for transmitting motion to said one of said planar die elements of said blade means. 